Tape laying machines for producing reinforced composite plastic structures have a tape laying head, usually oriented around the tape laying path, that includes a presser member contacting the tape for applying force against the tape to detrude the tape onto the work surface while following the changing contour of the work surface. Such a tape laying machine and more specifically a presser member is described in U.S. Pat. No. 4,954,204 assigned to the assignee of this application, the entire disclosure of which is incorporated herein by reference.
The tape is customarily a thermosetting or thermoplastic resin film often having fibrous (e.g. glass or carbon) reinforcement embedded therein. Such tape is applied to the work surface, usually a contoured mold surface, by a presser member, with some amount or pressure of force, in layers that are subsequently further consolidated, often with heat and pressure.
More recent designs of tape laying equipment, for making composite structures, employ segmented shoes in the presser member. These segmented shoes, which employ a plurality of individually movable blades or rollers have the advantage of improved conformation of the tape to the work surface, especially when simultaneous multiaxial changes in contour occur on the work surface. To further improve the performance of these segmented shoes it is known to use a flexible skid member between the shoe and the tape.
In applying the tape to the work surface it is known in the art to cause the tape, usually having a layer of paper on the one surface, to pass beneath, i.e. slide against, the flexible skid member, with the paper surface contacting the skid, while the movable components (i.e. blades or rollers) of the segmented shoe are pressing against the skid and thus the tape. The skid is attached at one end to a solid section of the presser member and at least equal to the width of the tape being employed. Passage of the tape along the bottom of the flexible skid member often does not produce undesirable movement, particularly lateral movement, of the membrane or skid. However, under certain conditions during the laying of the tape lateral motions of the flexible skid member can be and are experienced which produce undesirable shifting of a layer of tape with respect to the layer below and/or the work surface and other defects in the laminated structure of the molding. Shifting or bunching of the tape is especially vulnerable to occur when beginning the application of a new course or layer of tape over an existing layer of tape on the work surface or during laying a adjacent runs of tape. During such an operation the free end of the flexible skid member may move vertically and/or laterally while the presser member is being positioned for laying the next course of tape. As a consequence of such vertical and/or lateral motion the flexible skid member may not be in its proper position for laying the next course of tape. Such a condition can and does cause the tape to misalign or bunch up at the start of the course and results alignment and/or delamination defects in the composite structure. Thus, it is highly desirable to prevent undesirable motion of the flexible skid member of the presser member of the tape laying apparatus, while at the same time not restricting the advantageous and necessary motions of the presser member, particularly the blade or roller segment of the segmented shoe.